In some communications systems, such as those that are compliant to the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) technical standards, a communications controller may allocate network resources (e.g., time resources, frequency resources, or time-frequency resources) to a communications device so that the communications device may be able to communicate. The communications controller may signal the allocated network resources to the communications device in a transmission made over a control channel. Once the communications device knows about the allocated network resources, the communications device may make use of the allocated network resources to transmit or receive, depending on the type of the resource allocation.
Some control channels are transmitted within a region which is decided by parameters, for example, time domain duration (signaled by physical layer signaling in every subframe), system bandwidth, and so on. Such a control region can accommodate multiple control channels, e.g., a physical downlink control channel (PDCCH), and it is normally known where to search for these control channels. Therefore, the communications device generally knows where to search for the transmission. However, some control channels are transmitted within regions that are configured by radio resource control (RRC) signaling, e.g., a relay-physical downlink control channel (R-PDCCH) or a frequency-domain extension of the PDCCH, which may be configured by a communications controller. In order to simplify the search for these control channels, the communications controller may specify a search space for a communications device in which the communications device may search for the control channel targeted for it.